Engraving Methods and Techniques
As important as the gravers are, it is hard to understate the importance of the devices used to secure work while engraving. Or to say it another way, even a properly sharpened graver in experienced hands will be difficult to use if the workpiece is sliding across the bench. Knowing this it is not surprising to find that several tools have been developed to hold onto the work for cutting.
The simplest and cheapest tool is a pitch stick, described earlier in the section on filing. This is nothing more than a convenient length of wood that has a layer of pitch smeared on one end. The work is set into the softened pitch and pressed down to insure a grip, then the pitch is allowed to cool and solidify. The stick is held against the bench pin as the graver is moved against it. When cutting is complete the pitch is warmed slightly and the piece is removed. Alternate adhesive media include flake shellac and hot glue.
Figure 10.23 shows a top-of-the-line holding device, a weighty steel ball called an engravers block. This steel sphere is divided at its equator and mounted on a greased bearing to allow it to rotate easily. The top element is fitted with a vise that has many holes to receive holding pins. One side of the holding plate swivels, so by placing pins strategically and turning the plate as needed it is possible to hold almost any shape in the block. Tiny pieces can be secured with pitch onto a strip of wood that is then clamped into the device.
|Engraver’s block with universal adjustments.|
The gravers block is set into a felt or leather ring that allows it to be tilted at any angle. In conjunction with its free rotation, this makes the tool extremely responsive to even subtle movements as work is being moved under the cutting action of a graver. The gravers block is also a useful tool for chasing, stone setting and other “two-handed” tasks.
Working with the Graver
Elaborate designs or lengthy panels of text will almost certainly be given over to professional engravers, but it is useful to be able to cut a monogram or decorative line at the bench. In addition, goldsmiths who have confidence in their engraving skills will find themselves reaching for a graver to assist in clean up, to sharpen a detail, and to cut seats for stones. It is worth noting that every culture that has worked precious metals has invented a graver or similar cutting tool.
Imagine learning to play a sport or to dance only by reading about it and you will have a sense of the importance of practice when it comes to learning how to engrave. The following passage attempts to describe the cutting process, but no amount of reading or observation can take the place of sitting down with the tools to practice. Regular work with gravers, however, will teach subtle factors such as angle, force and roll if you keep at it. It is better to practice for 15 minutes every day than to labor for a couple hours once a month.
The proper stroke will involve a delicate ballet between tool and object as each is moved into the other. Dozens of muscles in the hands are constantly receiving information and reacting to it in the form of subtle adjustments of pressure and tilt. Attempt to remain relaxed as you cut, keeping your shoulder and arm muscles loose.
If the graver is properly sharpened it will slide through even tough metal relatively easily. If you are driving the tool with brute force something is wrong and the tool probably needs to be resharpened. Recognize this as a necessary part of the process and stop as soon as it is needed. Again think of a pencil – if the point has gone dull there is nothing for it but to stop and sharpen it!
To learn engraving, prepare many panels of copper or aluminum roughly 40 x 40 mm (1.5 x 1.5 inches) and 1.5 to 2 mm thick (16-12 gauge B&S). Secure a piece to a pitch stick or in a gravers block and practice making straight parallel lines such as shown in the top row of samples in figure 10.24. Avoid the temptation to “scoop” with the tool, allowing it instead to glide along its path. Stop when you get weary and return fresh another day.
|Suggestions for engraving exercises|
Next test your skills at making curved lines, following the patterns shown in the second row of the illustration. Strive for smooth curves and consistent line width. You will find this easiest if the metal plate is moving into the graver as the tool is sliding across the metal.
Finally, train yourself to create a cut line that goes from narrow to broad and back to narrow again. This “line of beauty” is a staple of engraving and will justify whatever time it takes to learn it. Some people make the cut in two stages, cutting a thin line first, then recutting over the same line, this time rolling the graver over slightly onto its side to broaden the line. The tool is rolled and pressed forward in a smooth motion, then straightened gradually to return to a narrow line. The samples in the bottom row of figure 10.24 offer some examples of patterns to be cut.
Having mastered these strokes you will be able to assemble them into almost any pattern. Figures 10.25 and 10.26 show some examples of decorative engraving intended to inspire your practice.
|Heraldic engraving. Silver. 1938 (Ernst Brephol, Anstadt)|
|Engraved medallion. Silver. 1877 (Private Collection, London)|
|Designs for machine engraving.|
This technique can be thought of as an extension of engraving in that a sharpened steel tool is used to cut away small bits of metal to create decorative patterns. The principal difference is that the work is guided under the tool by a machine set up in such a way that it produces regular, often repetitious strokes. The results, seen in figures 10.27 and 10.28, are hypnotically rich. Though rarely seen today outside of museums, the elaborate machines, called rose engines, that were developed in the heyday of engine turning are testimonials to ingenuity and inventive play.
The technique can be used to carve forms, for instance in plastic or ivory, but our focus here will be on its decorative use on flat surfaces. The technique is especially appropriate for decorative boxes, watch cases, writing implements, medallions, and similar objects that will be handled because the decorated surfaces disguise wear better than smooth surfaces. Transparent enamels appear very precious indeed upon engine turned surfaces.
Engine turning was developed in the middle of the last century in the context of the industrialization of jewelry production, but today it has been superseded by other more expedient methods. Still the process is intriguing and continues to offer rich possibilities for experimentation. It is included here for the interest of aficionados and with the hope that this lovely and intriguing process will not be forgotten. Goldsmiths wanting to pursue this process will need to research further and undertake personal experiments, but it is hoped that the following introduction will at least guide goldsmiths as they get started.
The concept of the machine can be seen in figure 10.29. As this shows, the basic elements are a sliding mount that holds a graver rigid against the metal and a bed on which the panel is mounted. This bed is moved in accordance with a template (here the corrugated strip along the left edge). A spring on the right side maintains pressure against the bed, forcing it to press against the template and in this case slide back and forth as it travels vertically. From this example one can see that by altering the tools, templates and direction of travel an endless variety of patterns can be cut.
The machine can be driven by hand or motor power, though most rely on electric motors today. One can imagine how this might be arranged when looking at figure 10.30 in which the templates are rotated on an axis. The rotating axle is mounted on springs so it can respond to the action of the feeler pin against the template profile, driving the template (and the workpiece, which is attached to the same axle) back and forth as it rotates. By having several templates mounted side by side as shown, a variety of patterns can be cut on the same machine.
We are all familiar (too familiar!) with objects like those shown in figure 10.31, the results of a device incorrectly called a pantograph. A pantograph is a mechanical device (figure 10.32) through which an existing pattern can be duplicated. By altering the points of pivot, the pattern can be enlarged or reduced in perfect proportion as shown. When a pantograph arm is connected to a miniature milling tool mounted in a small powerful motor, the result is a popular device shown in figures 10.33 and 10.34 called a pantograph engraving machine.
Because the actual cutting is done with a rotating bur the cut is very different from an engraved line, a distinction that is clear to goldsmiths but perhaps less obvious to others. The advantage of the machine is its great regularity. No particular hand skills or experience are required to use the machine. A worker secures the piece into position and guides the feeler along a template. This in turn passes the rotating bur against the metal where a line is cut. The advantage is that the letter or image is cut identically every time; the disadvantage is that there is no room for subtlety or nuance. A pantograph engraving machine is like a typewriter in this way, efficient but visually boring.
With the aid of additional attachments it is possible to work on other than flat surfaces, as is seen in figure 10.34 where a goblet is being engraved. In this way the pantograph machine can be adapted for use on concave or convex curved surfaces (the surface of a button), tubular shapes both outside and inside (micrometer collars, inside wedding band engraving), and conical metal surfaces like the goblet shown. It is also possible to mill completely through a piece of sheet metal, a process used for instance, to create brass stencils for spray painting letters.
Though little energy is given to traditional engraving in recent time, considerable effort has been devoted to developments along the lines of pantograph engraving. In the process called CAD/CAM (computer-aided design/computer-aided manufacturing), a tool is guided in the x, y, and z axis by a computer, making possible the development of forms from an image created on a computer screen.